OptionsMixin(fix[show_option]): Add deprecation warning for g parameter

why: The g parameter should emit DeprecationWarning like set_option() does
what:
- Add deprecation warning when g parameter is used
- Follow same pattern as set_option() (lines 669-671)
- Ensures backward compatibility while guiding users to global_

Author: tony

src/libtmux/options.py

@@ -1208,9 +1208,13 @@ def show_option(
         >>> MyServer().show_option('exit-unattached', global_=True)
         False
         """
+        if g:
+            warnings.warn("g argument is deprecated in favor of global_", stacklevel=2)
+            global_ = g
+
         return self._show_option(
             option=option,
-            global_=global_ or g,
+            global_=global_,
             scope=scope,
             ignore_errors=ignore_errors,
             include_hooks=include_hooks,